Silicon bronze alloys



United States Patent M SILICON BRONZE ALLOYS Robert A. Colton, Fanwood, N. J.,- assignor to American Smelting and Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application April 7, 1951, Serial No. 219,893

4 Claims. (Cl. 75-154) This invention relates to silicon bronze alloys and has as a primary object the provision of such alloys with improved properties.

Certain silicon bronze compositions, when cast in sand molds, often have a rough, reddish surface with an unattractive appearance. It will be understood that there are many articles made directly by casting without any subsequent polishing or machining. In such cases, it is desirable to have a nice bright looking, smooth yellow casting.

It has been found that, by incorporating critical amounts of arsenic in such silicon bronze compositions, as specified below, sand castings of such compositions can be made, consistently, to have a smooth, golden colored surface. This is in direct contrast to results obtained with castings of the same compositions but without the addition of arsenic.

Composition limits of the essential constituents of the various silicon bronze alloys embraced by the invention are: (a) 15% silicon, 0.051% arsenic, the balance copper; (b) alloy a with 0.252% manganese replacing an equivalent amount of copper; (c) alloy a with (Ll-1% tin replacing an equivalent amount of copper; (d) alloy a with 0.252% iron replacing an equivalent amount of copper. Minor impurities and non-essential constituents may be present to the extent that they do not adversely affect or destroy the beneficial effects of the arsenic content.

Tests have conclusively shown that the addition of arsenic according to the invention causes sand castings of silicon bronze to have, consistently, a smooth, golden colored, bright surface, While those made from the same compositions, but without arsenic, are often rough, red colored and unattractive. It has been found that the red, rough texture of such metal sand castings is entirely a surface condition; and that, by removing the outside skin 2,706,154 Patented Apr. 12, 1955 from both rough, red colored surface castings (with no arsenic) and bright yellow, smooth surface castings (with arsenic added) the alloy under the skin is identical in color and texture in the two cases.

.Extensive tests have indicated that the addition of the arsenic according to the invention produces no adverse effects on the tensile strength or other mechanical properties of the casting. Extensive tests have also shown that the alloy according to the invention has excellent ability to stand repeated remeltings Without the arsenic burning out. This is obviously of advantage in cases where the foundry process uses its own scrap continuously.

What is claimed is:

1. In a method of insuring the formation of a bright surface upon sand casting alloys consisting of 15% silicon and arsenic below 0.05% with the balance copper, the step of incorporating into the said alloy to be cast an arsenic content in the range .051% and casting the alloy in a sand mold to an article of the shape and size of the finished product.

2. A method according to claim 1 in which an equivalent amount of copper in said alloy is replaced by 0.252% manganese.

3. A method according to claim 1 in which an equivalent amount of copper in said alloy is replaced by 0.1-1% tin.

4. A method according to claim 1 in which an equivalent amount of copper in said alloy is replaced by 0.252% iron.

References Cited in the file of this patent UNITED STATES PATENTS 1,936,397 Jennison Nov. 21, 1933 2,035,414 Wilkins Mar. 24, 1936 2,062,448 Deitz et al Dec. 1, 1936 2,126,246 Deitz et a1 Aug. 9, 1938 2,338,756 Crampton et a1 Jan. 11, 1944 OTHER REFERENCES I. Inst. of Metals, 4, page 173 (1910).

Metallurgy of Copper by Newton and Wilson, published by John Wiley and Sons, 1942, pages 392, 393, 394 and 395.

Woldman et al.: Engineering Alloys, 2nd edition (1945), published by Amer. Soc. for Metals, pages 229 and 242.

A. S. T. M. Standards, 1949, Part 2, Non-Ferrous Metals, pages 124, 286 and 333. 

1. IN A METHOD OF INSURING THE FORMATION OF A BRIGHT SURFACE UPON SAND CASTING ALLOYS CONSISTING OF 1-5% SILICON AND ARSENIC BELOW 0.05% WITH THE BALANCE COPPER, THE STEP OF INCORPORATING INTO THE SAID ALLOY TO BE CAST AN ARSENIC CONTENT IN THE RANGE 05-1% AND CASTING THE ALLOY IN A SAND MOLD TO AN ARTICLE OF THE SHAPE AND SIZE OF THE FINISHED PRODUCT. 